I've read where many people say not to try to use propane at altitude or at any level inside a tent for sleeping and to use wood. Any type of burning is going to give off carbon monoxide, so I'm not quite sure why they say that. Anyway, I have a camper with a propane furnace, but whenever I don't want to operate the generator that's needed to run the thermostat and blower motor I use a Mr Heater that screws right into a 20# or 30# propane bottle. Regardless of which one I use, I always have two carbon monoxide/smoke detectors (I always have a backup running just in case) and one or more windows cracked open a few inches for fresh air as a safety precaution. You can get them in one, two, or three to a unit, but even one will burn more propane than the Buddy Heater because they put out a lot more BTUs even on low. I usually figure 5 or 6 nights on low with a 20# bottle and I've used them up to about 8000' with no problem. If you go that route, use the safety precautions I mentioned.